Medecins Sans Frontieres has ended its rescue operations in the Mediterranean after eight months at sea, the medical charity said Tuesday.
MSF said that it conducted more than 120 search-and-rescue operations and rescued 20,129 people.
"None of the people on board of the unseaworthy boats we rescued would have made it to safety without intervention," said Stefano Argenziano, MSF's manager of migration operations.
While stressing the importance of these operations, Argenziano said that "we are doctors and search and rescue shouldn't be our job."
"We very much hope that European resources will be sufficient in 2016 and that our boats will not be required," Argenziano said in a statement.
In December, UN refugee agency UNHCR and the International Organization for Migration (IOM) said that 972,500 people had entered the continent via the Mediterranean Sea, more than four times as many as in 2014.
More than 3,600 people died or went missing on the dangerous sea routes in 2015, compared to nearly 3,300 the previous year, they said.
MSF stressed that it would remain on standby to intervene if European Union countries failed to assist the thousands of people fleeing to Europe.
"It is absolutely crucial that the EU and the member states provide resources which are dedicated, and proactive, capable of reacting within an hour of the distress call," said Brice de la Vinge, MSF's director of operations. "But search and rescue cannot stop deaths at sea."
What will end deaths at sea, MSF said, was "the implementation of policies and practices that provide safe and legal channels to the EU and eliminate the need for people to use smugglers and overcrowded rubber and wooden boats to reach the shores of Europe."